Performance problem: 1.000 queries over a 1.000.000 rows table

Question

Hi everybody!
I have a difficult performance problem: I use JDBC over an ORACLE database. I need to build a map using data from a table with around 1.000.000 rows. My query is very simple (see the code) and takes an average of 900 milliseconds, but I must perform around 1.000 queries with different parameters. The final result is that user must wait several minutes (plus the time needed to draw the map and send it to the client)
The code, very simplified, is the following:
String sSQLCreateView =
"CREATE VIEW " + sViewName + " AS " +
"SELECT RIGHT_ASCENSION, DECLINATION " +
"FROM T_EXO_TARGETS " +
"WHERE (RIGHT_ASCENSION BETWEEN " + dRaMin + " AND " + dRaMax + ") " +
"AND (DECLINATION BETWEEN " + dDecMin + " AND " + dDecMax + ")";
String sSQLSentence =
"SELECT COUNT(*) FROM " + sViewName +
" WHERE (RIGHT_ASCENSION BETWEEN ? AND ?) " +
"AND (DECLINATION BETWEEN ? AND ?)";
PreparedStatement pstmt = in_oDbConnection.prepareStatement(sSQLSentence);
for (int i = 0; i < 1000; i++)
pstmt.setDouble(1, a);
pstmt.setDouble(2, b);
pstmt.setDouble(3, c);
pstmt.setDouble(4, d);
ResultSet rset = pstmt.executeQuery();
X = rset.getInt(1);
I have yet created index with RIGHT_ASCENSION and DECLINATION fields (trying different combinations).
I have tried yet multi-threads, with very bad results
Has anybody a suggestion ?
Thank you very much!

Answer 1

How many total rows are there likely to be in the View you create?
Perhaps just do a select instead of a view, and loop thru the resultset totalling the ranges in java instead of trying to have 1000 queries do the job. Something like:
int     iMaxRanges = 1000;
int     iCount[] = new int[iMaxRanges];
class Range implements Comparable
     float fAMIN;
     float fAMAX;
     float fDMIN;
     float fDMAX;
     float fDelta;
     public Range(float fASC_MIN, float fASC_MAX, float fDEC_MIN, float fDEC_MAX)
          fAMIN = fASC_MIN;
          fAMAX = fASC_MAX;
          fDMIN = fDEC_MIN;
          fDMAX = fDEC_MAX;
     public int compareTo(Object range)
          Range     comp = (Range)range;
          if (fAMIN < comp.fAMIN)
               return -1;
          if (fAMAX > comp.fAMAX)
               return 1;
          if (fDMIN < comp.fDMIN)
               return -1;
          if (fDMAX > comp.fDMAX)
               return 1;
          return 0;
List     listRanges = new ArrayList(iMaxRanges);
listRanges.add(new Range(1.05, 1.10, 120.5, 121.5));
//...etc.
String sSQL =
"SELECT RIGHT_ASCENSION, DECLINATION FROM T_EXO_TARGETS " +
"WHERE (RIGHT_ASCENSION BETWEEN " + dRaMin + " AND " + dRaMax + ") " +
"AND (DECLINATION BETWEEN " + dDecMin + " AND " + dDecMax + ")";
Statement stmt = in_oDbConnection.createStatement();
ResultSet rset = stmt.executeQuery(sSQL);
while (rset.next())
     float fASC = rset.getFloat("RIGHT_ASCENSION");
     flaot fDEC = rset.getFloat("DECLINATION");
     int iRange = Collections.binarySearch(listRanges, new Range(fASC, fASC, fDEC, fDEC));
     if (iRange >= 0)
          ++iCount[iRange];